Also reconsider the fee when lightning network is not yet here.
The lightning network is already here but there's a limit to how much you can transact afaik.
For now its possible because of very less people were using the bitcoin so the country where it is most used might come at the partuclar time zone for now but in future people usues oly cryptos the fee will not be dependabe much on the time zones.
Or during those hours there could be a lot of blocks mined then on the next hour there would be less.
I do not know how accurate this study is but if there is any atom of truth then bitcoin is not ready yet to be used as a global currency. As we are presenting bitcoin as a global currency we are meant to eradicate any trace of zoning. Bitcoin fee should be bitcoin fee anywhere, anytime globally.
Let's not forget, there are ways to avoid transaction fee if they become a problem again in the future. We can also spend Bitcoin off chain where we don't have to use transaction fees or use the lightning network.